In recent years, there has been considerable interest in developing methods for assembling nanoscale building blocks into periodic, functional materials. See Storhoff et al., J. Clust. Sci., 8:179 (1997) and references cited therein, and Brousseau et al., J. Am. Chem. Soc., 120:7645 (1998). These methods rely on access to both novel building block compositions and assembly strategies.
With regard to the former, both inorganic and organic compositions are now available. Importantly, some of these building blocks are accessible in macroscopic quantities and in monodisperse form. For example, a variety of methods exist for preparing monodisperse samples of CdS and CdSe particles (Murray et al., J. Am. Chem. Soc., 115:8706 (1993); Weller, Angew. Chem., Int. Ed. Engl., 32:41 (1993); Wang and Herron, J. Phys. Chem., 95:525 (1991)) and gold particles (Grabar et al., J. Anal Chem., 67:735 (1995); Frens, Nature Phys. Sci., 241:20 (1973); Hayat, M. A. (ed.), Colloidal Gold: Principles, Methods and Applications (Academic, San Diego, 1991)) with diameters ranging from 1 to 40 nm. Studies involving these well-defined inorganic particles not only have led to a greater understanding of quantum confinement effects but also the development of new and useful spectroscopic methods (Freeman et al., Science, 267:1629 (1995); Zhu et al., J. Am. Chem. Soc., 119:235 (1997)) and detection technologies (Mirkin et al., Nature, 382:607 (1996); Elghanian et al., Science, 277:1078 (1997); Storhoff et al., J. Am. Chem. Soc., 120:1959 (1998)). Similarly, a great deal has been learned from the synthesis, characterization, and study of polymer particle compositions. Goodwin et al., Colloid Polym. Sci., 525:464 (1974); Goodwin et al., Colloid Polym. Sci., 257:61 (1979); Schmitt et al., Adv. Mater., 9:61 (1997); José-Yacamán et al., Appl. Phys. Lett., 7:913 (1969); Olsen and Kafafi, J. Am. Chem. Soc., 113:7758 (1991); Spatz et al., Adv. Mater., 8:337 (1996) However, far less is known about such systems with nanoscale dimensions (<100 nm).
The development of synthetic methods for preparing structures consisting of nanoparticle cores and organic polymer shells on this size scale would give entry into a new and versatile class of hybrid nanoparticle building blocks. Importantly, if it were possible to control the composition and thicknesses of the polymer shells, one would have unprecedented control over the chemical and physical properties of these novel materials.